Methods of hydrating mucosal surfaces

ABSTRACT

A method of hydrating nasal airway surfaces in a subject in need of such treatment comprises topically applying a sodium channel blocker to a nasal airway surface of the subject in an amount effective to inhibit the reabsorption of water by the surface. The channel blocker may be a pyrazinoylguanidine sodium channel blocker, such as benzamil, phenamil, amiloride, or a pharmaceutically acceptable salts thereof. The method may further comprise the step of topically applying a P2Y 2  receptor agonist to a nasal airway surface of the subject in an amount effective to stimulate chloride secretion by the nasal airway surface. In a preferred embodiment, the sodium channel blocker is a covalent conjugate of a pyrazinoylguanidine sodium channel blocker and a non-absorbable carrier moiety (e.g., albumin, polyethylene glycol). Such compounds may also be administered to other mucosal surfaces where it is desired to inhibit the reabsorption of water.

RELATED APPLICATIONS

[0001] This application claims priority from provisional applicationSer. No. 60/104,999, filed Oct. 20, 1998, the disclosure of which isincorporated by reference herein in its entirety.

FIELD OF THE INVENTION

[0002] The present invention concerns methods of hydrating nasal airwaysurfaces in patients in need of such treatment, along with compounds andcompositions usefull for carrying out such methods.

BACKGROUND OF THE INVENTION

[0003] The current therapy for hydrating nasal airway surfaces is toapply normal saline via drops or spray delivery devices. Thedisadvantage of this simple approach is that the duration of effect isshort. It would be desireable to provide a way to achieve a more lastinghydration of nasal airway surfaces.

[0004] U.S. Pat. No. 5,789,391 to Jacobus describes methods of treatingsinusitis with uridine triphosphates and related compounds such as UTPor P¹,P⁴-di(uridine-5′ tetraphosphate (U₂P₄) in an amount effective topromote drainage of congested fluid in the sinuses by hydrating mucoussecretions or by stimulating ciliary beat frequency in the sinuses.

[0005] U.S. Pat. No. 4,501,729 to Boucher describes the use ofrespirable or non-respirable amiloride to hydrate airway mucoussecretions, and U.S. Pat. No. 5,656,256 to Boucher and Stutts describesthe use of respirable or non-respirable benzamil and phenamil to hydratelung mucous secretions. The use of amiloride, benzamil or phenamil tohydrate nasal airway surfaces is neither disclosed nor suggested.

SUMMARY OF THE INVENTION

[0006] A first aspect of the present invention is a method of hydratingnasal airway surfaces in a subject in need of such treatment. The methodcomprises topically applying a sodium channel blocker to a nasal airwaysurface of the subject in an amount effective to inhibit thereabsorption of water by the nasal airway surface. The channel blockermay be a pyrazinoylguanidine sodium channel blocker, such as benzamil,phenamil, amiloride, or a pharmaceutically acceptable salt thereof.

[0007] The method may further comprise the step of topically applying aP2Y₂ receptor agonist to a nasal airway surface of the subject in anamount effective to stimulate chloride secretion, and thereby stimulatewater secretion, by the nasal airway surface.

[0008] A second aspect of the present invention is a method of hydratingmucosal surfaces such as airway surfaces in a subject in need of suchtreatment, comprising topically applying a sodium channel blocker to amucosal surface such as an airway surface of the subject in an amounteffective to inhibit the reabsorption of water by the surface, whereinthe sodium channel blocker is a covalent conjugate of apyrazinoylguanidine sodium channel blocker and a non-absorbable carriermoiety (e.g., polyethylene glycol, albumin; carbohydrate).

[0009] Again, the method may further comprise the step of topicallyapplying a P2Y₂ receptor agonist to a mucosal surface such as an airwaysurface of the subject in an amount effective to stimulate chloridesecretion by the surface.

[0010] A third aspect of the present invention is a pharmaceuticalformulation, comprising a sodium channel blocker in a pharmaceuticallyacceptable carrier (e.g., an aqueous carrier solution); wherein thesodium channel blocker is a covalent conjugate of a pyrazinoylguanidinesodium channel blocker and a non-absorbable carrier moiety; preferablysubject to the proviso that the non-absorbable carrier moiety is notbovine serum albumin or rabbit serum albumin. The composition mayfurther contain a P2Y₂ receptor agonist.

[0011] A fourth aspect of the present invention is a compound useful asa sodium channel blocker, the compound comprising a covalent conjugateof a pyrazinoylguanidine sodium channel blocker and a non-absorbablecarrier moiety; preferably subject to the proviso that thenon-absorbable carrier moiety is not bovine serum albumin, rabbit serumalbumin or agarose. For example, the carrier moiety can be polyethyleneglycol or human serum albumin, or a carbohydrate.

[0012] A fifth aspect of the present invention is the use of compoundsas described above for the preparation of a medicament for the treatmentof disorders as described herein.

[0013] The present invention is explained in greater detail in thespecification below.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0014] The term “airway surface” as used refers to airway surfaces belowthe larynx and in the lungs, as well as air passages in the head,including the sinuses, in the region above the larynx.

[0015] The term “nasal airway surface” as used herein refers to theairways and associated air passages in the head, including the sinuses,in the region above the larynx. This definition excludes airways belowthe larynx, which have been the target of drug delivery for differentpurposes.

[0016] The term alkyl or loweralkyl as used herein refers to C1 to C4alkyl, which may be linear or branched and saturated or unsaturated.Cycloalkyl is specified as such herein, and is typically C3, C4 or C5 toC6 or C8 cycloalkyl. Alkenyl or loweralkenyl as used herein likewiserefers to C1 to C4 alkenyl, and alkoxy or loweralkoxy as used hereinlikewise refers to C1 to C4 alkoxy. Halo as used herein refers to anyhalogen, such as chloro, fluoro, bromo, or iodo.

[0017] The term “non-absorbable carrier moiety” as used herein refers toa functional group that serves to trap the compound containing the groupon airway surfaces, or adhere the compound to airway surfaces, andpartly or wholly inhibits the absorption of the compound by the surfaceon which it is deposited.

[0018] Subjects that may be treated by the methods of the presentinvention include patients afflicted with cystic fibrosis, primaryciliary dyskinesia, chronic bronchitis, chronic obstructive airwaydisease, artificially ventilated patients, patients with acutepneumonia, etc. The present invention may be used to obtain a sputumsample from a patient by administering the active compounds to at leastone lung of a patient, and then inducing or collecting a sputum samplefrom that patient.

[0019] Subjects that may be treated by the method of the presentinvention also include patients being nasally administered supplementaloxygen (which tends to dry the airway surfaces), patients afflicted withan allergic disease or response (e.g., an allergic response to pollen,dust, animal hair or particles, insects or insect particles, etc.) thataffects nasal airway surfaces, patients afflicted with a bacterialinfection (e.g., staphylococcus infections such as staphylococcus aureusinfections, Hemophilus influenza infections, streptococcus pneumoniaeinfections, pseudomonas infections, etc.) of the nasal airway surfaces,an inflammatory disease that affects nasal airway surfaces, or patientsafflicted with sinusitis (wherein the active agent or agents areadministered to promote drainage of congested mucous secretions in thesinuses by administering an amount effective to promote drainage ofcongested fluid in the sinuses).

[0020] The present invention may be used to hydrate mucosal surfacesother than airway surfaces. Such other mucosal surfaces includegastrointestinal surfaces, oral surfaces, genito-ureteral surfaces,ocular surfaces or surfaces of the eye, the inner ear, and the middleear. For example, the active compounds of the present invention may beadministered by any suitable means, including orally or rectally, in anamount effective to combat constipation in a subject.

[0021] The present invention is concerned primarily with the treatmentof human subjects, but may also be employed for the treatment of othermammalian subjects, such as dogs and cats, for veterinary purposes.

[0022] 1. Active agents

[0023] Pyrazinoylguanidine sodium channel blockers are disclosed in U.S.Pat. No. 3,313,813 to Cragoe. (Applicant specifically intends that thedisclosure of this and all other U.S. Patent references cited herein beincorporated by reference herein in their entirety).

[0024] Amiloride, one particular pyrazinoylguanidine sodium channelblocker, is described at Merck Index Registry No. 426 (12th Ed. 1996).

[0025] Benzamil (also known as3,5-diamino-6-chloro-N-(benzylaminoaminomethylene)pyrazinecarboxamide)and phenamil (also known as3,5-diamino-6-chloro-N-(phenylaminoaminomethylene)pyrazinecarboxamide)are known compounds and are disclosed in U.S. Pat. No. 3,313,813 to E.Cragoe (applicant specifically intends that the disclosure of this andall other patents cited herein be incorporated herein by reference).

[0026] Various additional pyrazinoylguanidine sodium channel blockersthat are amiloride analogs are disclosed and described in T. Kleyman andE. Cragoe, Amiloride and its Analogs as Tools in the Study of IonTransport, J. Membrane Biol. 105, 1-21 (1988).

[0027] Specific examples of active compounds that may be used to carryout the present invention are the pyrazinoylguanidine sodium channelblockers disclosed in U.S. Pat. No. 3,313,813, incorporated by referenceabove. Such compounds have the formula:

[0028] wherein:

[0029] X is selected from the group consisting of chloro, bromo, iodo,loweralkyl, lower-cycloalkyl having from 3 to 7 carbons, phenyl,chlorophenyl, bromophenyl, X′-thio and X′-sulfonyl wherein X′ isselected from the group consisting of loweralkyl and phenyl-loweralkyl.Preferably, X is chloro.

[0030] Y is selected from the group consisting of hydroxyl, mercapto,loweralkyloxy, loweralkylthio, chloro, loweralkyl, lowercycloalkylhaving from 3 to 6 carbons, phenyl, amino having the structure:

[0031] wherein:

[0032] R is selected from the group consisting of hydrogen, amino,amidino, lower-cycloalkyl having 3 to 6 carbon atoms, loweralkyl,hydroxyloweralkyl, halo-loweralkyl, lower-(cycloalkylalkyl) having 3 to6 carbons in the ring, phenyl-loweralkyl, lower-(alkylaminoalkyl),lower-alkenyl, phenyl, halophenyl, and lower-alkylphenyl. In onepreferred embodiment, Y is chloro; in another preferred embodiment, Y isamino.

[0033] R₁ is selected from the group consisting of hydrogen, loweralkyl,loweralkenyl, and additionally;

[0034] R and R₁ can be joined to form a lower alkylene.

[0035] R₂ is selected from the group consisting of hydrogen andloweralkyl. Preferably, R, R₁, and R₂ are hydrogen.

[0036] R₃ and R₄ respectively are independently selected from the groupconsisting of hydrogen, loweralkyl, hydroxy-loweralkyl,phenyl-loweralkyl, (halophenyl)-loweralkyl, lower-(alkylphenylalkyl),(loweralkoxyphenyl)-loweralkyl, naphthyl-loweralkyl,(octahydro-1-azocinyl)-loweralkyl, pyridyl-loweralkyl, and loweralkylradicals linked to produce with the nitrogen atom to which they areattached a 1-pyrrolidinyl, piperidino, morpholino, and a4-loweralkyl-piperazinyl group, and phenyl. Preferably, R₃ is hydrogen,phenyl, or phenylalkyl. Preferably, R₄ is hydrogen.

[0037] 2. Pharmaceutically acceptable salts

[0038] The term “active agent” as used herein, includes thepharmaceutically acceptable salts of the compound, such as (but notlimited to) benzamil hydrochloride or phenamil hydrochloride.Pharmaceutically acceptable salts are salts that retain the desiredbiological activity of the parent compound and do not impart undesiredtoxicological effects. Examples of such salts are (a) acid additionsalts formed with inorganic acids, for example hydrochloric acid,hydrobromic acid, sulfuric acid, phosphoric acid, nitric acid and thelike; and salts formed with organic acids such as, for example, aceticacid, oxalic acid, tartaric acid, succinic acid, maleic acid, fumaricacid, gluconic acid, citric acid, malic acid, ascorbic acid, benzoicacid, tannic acid, palmitic acid, alginic acid, polyglutamic acid,naphthalenesulfonic acid, methanesulfonic acid, p-toluenesulfonic acid,naphthalenedisulfonic acid, polygalacturonic acid, and the like; and (b)salts formed from elemental anions such as chlorine, bromine, andiodine.

[0039] Active agent used to prepare compositions for the presentinvention may alternatively be in the form of a pharmaceuticallyacceptable free base of active agent. Because the free base of thecompound is less soluble than the salt, free base compositions areemployed to provide more sustained release of active agent to the lungs.Active agent present in the lungs in particulate form which has not goneinto solution is not available to induce a physiological response, butserves as a depot of bioavailable drug which gradually goes intosolution.

[0040] 3. Formulations and administration

[0041] A third aspect of the present invention is a pharmaceuticalformulation, comprising a sodium channel blocker in a pharmaceuticallyacceptable carrier (e.g., an aqueous carrier solution); wherein thesodium channel blocker is a covalent conjugate of a pyrazinoylguanidinesodium channel blocker and a non-absorbable carrier moiety; preferablysubject to the proviso that the non-absorbable carrier moiety is notbovine serum albumin or rabbit serum albumin. In general, the sodiumchannel blocker is included in the composition in an amount effective toinhibit the reabsorption of water by airway surfaces, particularly nasalairway surfaces. As discussed below, the composition may furthercomprise a P2Y₂ receptor agonist or a pharmaceutically acceptable saltthereof (also sometimes referred to as an “active agent” herein). TheP2Y₂ receptor agonist is typically included in an amount effective tostimulate chloride and water secretion by airway surfaces, particularlynasal airway surfaces.

[0042] The active compounds disclosed herein may be administered to thenasal airway surfaces of a patient by any suitable means, including as aspray, mist, or droplets of the active compounds in a pharmaceuticallyacceptable carrier such as physiological saline solution or distilledwater. For example, the active compounds may be prepared as formulationsand administered as described in U.S. Pat. No. 5,789,391 to Jacobus, thedisclosure of which is incorporated by reference herein in its entirety.

[0043] In one preferred embodiment they are administered byadministering an aerosol suspension of respirable or non-respirableparticles (preferably non-respirable particles) comprised of the activecompound, which the subject inhales through the nose. The respirable ornon-respirable particles may be liquid or solid. The quantity of activeagent included may be an amount sufficient to achieve dissolvedconcentrations of active agent on the nasal airway surfaces of thesubject of from about 10⁻⁷ to about 10⁻³ Moles/liter, and morepreferably from about 10⁻⁶ to about 10⁻⁴ Moles/liter.

[0044] In one embodiment of the invention, the particulate active agentcomposition may contain both a free base of active agent and apharmaceutically acceptable salt such as benzamil hydrochloride orphenamil hydrochloride to provide both early release of and sustainedrelease of active agent for dissolution into the mucous secretions ofthe nose. Such a composition serves to provide both early relief to thepatient, and sustained relief over time. Sustained relief, by decreasingthe number of daily administrations required, is expected to increasepatient compliance with a course of active agent treatments.

[0045] Solid or liquid particulate active agent prepared for practicingthe present invention should as noted above include particles ofrespirable or non-respirable size: that is, for respirable particles,particles of a size sufficiently small to pass through the mouth andlarynx upon inhalation and into the bronchi and alveoli of the lungs,and for nonrespirable particles, particles sufficiently large to beretained in the nasal airway passages rather than pass through thelarynx and into the bronchi and alveoli of the lungs. In general,particles ranging from about 1 to 5 microns in size (more particularly,less than about 4.7 microns in size) are respirable. Particles ofnon-respirable size are greater than about 5 microns in size, up to thesize of visible droplets. Thus, for nasal administration, a particlesize in the range of 10-500 μm may be used to ensure retention in thenasal cavity.

[0046] The dosage of active compound will vary depending on thecondition being treated and the state of the subject, but generally maybe an amount sufficient to achieve dissolved concentrations of activecompound on the nasal airway surfaces of the subject of from about 10⁻⁹to about 10⁻³ Moles/liter, and more preferably from about 10⁻⁶ to about3×10⁻⁴ Moles/liter. Depending upon the solubility of the particularformulation of active compound administered, the daily dose may bedivided among one or several unit dose administrations. The daily doseby weight may range from about 0.1, 0.5 or 1 to 10 or 20 milligrams ofactive agent particles for a human subject, depending upon the age andcondition of the subject. A currently preferred unit dose is about 0.5,1 or 2 milligrams of active agent given at a regimen of fouradministrations per day. The dosage may be provided as a prepackagedunit by any suitable means (e.g., encapsulating in a gelatin capsule).

[0047] Pharmaceutical formulations suitable for nasal administrationinclude formulations of solutions, emulsions, suspensions and extracts.See generally, J. Naim, Solutions, Emulsions, Suspensions and Extracts,in Remington: The Science and Practice of Pharmacy, chap. 86(19^(th) ed1995). Pharmaceutical formulations suitable for nasal administration maybe prepared as described in U.S. Pat. Nos. 4,389,393 to Schor; 5,707,644to Illum; 4,294,829 to Suzuki; and 4,835,142 to Suzuki; the disclosuresof which are incorporated by reference herein in their entirety.

[0048] In the manufacture of a formulation according to the invention,active agents or the physiologically acceptable salts or free basesthereof are typically admixed with, inter alia, an acceptable carrier.The carrier must, of course, be acceptable in the sense of beingcompatible with any other ingredients in the formulation and must not bedeleterious to the patient. The carrier may be a solid or a liquid, orboth, and is preferably formulated with the compound as a unit-doseformulation, for example, a capsule, which may contain from 0.5% to 99%by weight of the active compound. One or more active compounds may beincorporated in the formulations of the invention, which formulationsmay be prepared by any of the well-known techniques of pharmacyconsisting essentially of admixing the components.

[0049] Mists or aerosols of liquid particles comprising the activecompound may be produced by any suitable means, such as by a simplenasal spray with the active agent in an aqueous pharmaceuticallyacceptable carrier, such as sterile saline solution or sterile water.Administration may be with a pressure-driven aerosol nebulizer or anultrasonic nebulizer. See, e.g., U.S. Pat. Nos. 4,501,729 and 5,656,256.Suitable formulations for use in a nasal droplet or spray bottle or innebulizers consist of the active ingredient in a liquid carrier, theactive ingredient comprising up to 40% w/w of the formulation, butpreferably less than 20% w/w. The carrier is typically water (and mostpreferably sterile, pyrogen-free water) or a dilute aqueous alcoholicsolution, preferably made isotonic with body fluids by the addition of,for example, sodium chloride. Optional additives include preservativesif the formulation is not made sterile, for example, methylhydroxybenzoate, antioxidants, flavoring agents, volatile oils,buffering agents and surfactants.

[0050] Mists or aerosols of solid particles comprising the activecompound may likewise be produced with any solid particulate medicamentaerosol generator. Aerosol generators for administering solidparticulate medicaments to a subject produce particles which arerespirable or non-respirable, as explained above, and generate a volumeof mist or aerosol containing a predetermined metered dose of amedicament at a rate suitable for human administration. One illustrativetype of solid particulate aerosol generator is an insufflator. Suitableformulations for administration by insufflation include finelycomminuted powders which may be delivered by means of an insufflator ortaken into the nasal cavity in the manner of a snuff. In theinsufflator, the powder (e.g., a metered dose thereof effective to carryout the treatments described herein) is contained in capsules orcartridges, typically made of gelatin or plastic, which are eitherpierced or opened in situ and the powder delivered by air drawn throughthe device upon inhalation or by means of a manually-operated pump. Thepowder employed in the insufflator consists either solely of the activeingredient or of a powder blend comprising the active ingredient, asuitable powder diluent, such as lactose, and an optional surfactant.The active ingredient typically comprises from 0.1 to 100 w/w of theformulation. A second type of illustrative aerosol generator comprises ametered dose inhaler. Metered dose inhalers are pressurized aerosoldispensers, typically containing a suspension or solution formulation ofthe active ingredient in a liquified propellant. During use thesedevices discharge the formulation through a valve adapted to deliver ametered volume, typically from 10 to 150 μl to produce a fine particlespray containing the active ingredient. Suitable propellants includecertain chlorofluorocarbon compounds, for example,dichlorodifluoromethane, trichlorofluoromethane,dichlorotetrafluoroethane and mixtures thereof. The formulation mayadditionally contain one or more co-solvents, for example, ethanol,surfactants (such as oleic acid or sorbitan trioleate), antioxidants andsuitable flavoring agents.

[0051] Compositions containing respirable or non-respirable dryparticles of micronized active agent may be prepared by grinding the dryactive agent with a mortar and pestle, and then passing the micronizedcomposition through a 400 mesh screen to break up or separate out largeagglomerates.

[0052] The particulate active agent composition may optionally contain adispersant which serves to facilitate the formation of an aerosol. Asuitable dispersant is lactose, which may be blended with the activeagent in any suitable ratio (e.g., a 1 to 1 ratio by weight).

[0053] 4. Covalent conjugates

[0054] As noted above, also disclosed is a method of hydrating nasalairway surfaces in a subject in need of such treatment, comprisingtopically applying a sodium channel blocker to a nasal airway surface ofthe subject in an amount effective to inhibit the reabsorption of waterby the nasal airway surface, wherein the sodium channel blocker is acovalent conjugate of a pyrazinoylguanidine sodium channel blocker and anon-absorbable carrier moiety. The non-absorbable carrier moiety may bea carbohydrate, protein, peptide, amino acid, polyamine, or watersoluble linear polymer, which may be directly linked to the sodiumchannel blocker or linked through an intermediate linking group such asan alkylene group. Other suitable carrier moieties include erythritoland xylotol.

[0055] Water soluble linear polymers useful as carrier moieties includepolyvinylpyrrolidone, polyethylene glycol, nonylphenol ethoxylates, andpolyvinyl alcohol.

[0056] Carbohydrates useful as carrier moieties include sugars andpolysaccharides (including charged and uncharged polysaccharides), suchas dextran, lactose, sialic acid and mannitol. An additional example isagarose.

[0057] Proteins or peptides useful as carrier moieties include albumin(for example, human serum albumin) and protamine.

[0058] Amino acids useful for carrying out the present invention includeall twenty standard amino acids (alanine, valine, leucine, isoleucine,proline, phenylalanine, tryptophan, methionine, glycine, serine,threonine, cysteine, tyrosine, asparagine, glutamine, aspartic acid,glutamic acid, lysine, arginine, and histidine), in either the D or Lconfiguration.

[0059] Polyamines useful for carrying out the present invention includespermine and spermidine.

[0060] In one embodiment, the conjugate has the formula:

[0061] wherein:

[0062] X, Y, and R₂ are as described above, and Z is the non-absorbablecarrier moiety covalently linked, directly or indirectly, to theadjacent nitrogen atom.

[0063] An of a variety of approaches for linking the pyrazinoylguanidinesodium channel blocker to the non-absorbable moiety may be employed, asdiscussed below.

[0064] A direct linkage by a caproate linker may be employed by reactingthe nonabsorbable moiety with intermediates as follows, in accordancewith known techniques:

[0065] where X, Y, and R₂ are as given above.

[0066] Spacer linkers may be employed with intermediates as follows:

[0067] +aminohexyl (agarose)

[0068] (T. Kleyman and E. Cragoe, J. Membrane Biol. 105, 1 (1988)(FIG.2) where X, Y, and R₂ are as given above.

[0069] General linkers may be employed with intermediates as follows:

[0070] where X and Y are as described above.

[0071] Techniques for forming conjugates are known. A covalent conjugateof amiloride and bovine or rabbit serum albumin for use in creatinganti-amiloride antibodies is disclosed in T. Kleyman et al., NewAmiloride Analogue as Hapten to Raise Anti-Amiloride Antibodies, Am. J.Physiol. 250, C165-C170 (1986). This same technique can be performedwith other amiloride analogs, and with other proteins or peptides. Thus,for example, a covalent conjugate of amiloride and analogs thereof, suchas benzamil or phenamil, with human serum albumin can be produced inlike manner.

[0072] Covalent conjugates of amiloride and SEPHAROSE™ brand agarose (apolysaccharide) are described in T. Kleyman et al., supra, and in D.Benos et al., Proc. Natl. Acad. Sci. USA 83, 8525-8529 (1986). Differentbrands, forms, and molecular weights of agarose may be employed, orother polysaccharides employed, or different amiloride analogs such asbenzamil or phenamil may be employed, to make additional covalentconjugates by similar techniques.

[0073] 5. P2Y₂ Receptor agonists

[0074] The methods described above may further comprise the step oftopically applying a P2Y₂ receptor agonist to a nasal airway surface ofthe subject in an amount effective to stimulate chloride secretion bythe nasal airway surface. The concurrent topical application may becarried out by combining the P2Y2 receptor agonists with the activeagent described above in a common pharmaceutically acceptable carriersolution. The agonist may be UTP or an analog thereof, as described inU.S. Pat. Nos. 5,789,391; 5,656,256 or 5,292,498, the disclosures ofwhich are to be incorporated by reference herein in their entirety.Particularl preferred agonists are UTP, the UTP analog uridine5′-O-(3-thiotriphosphate) (or “UTP gamma S”), or the UTP analog P¹,P⁴-di(uridine-5′) tetraphosphate (or “U₂P₄”).

[0075] Concurrent application refers to essentially co-extensiveapplication, or application to the same portion or portions of the nasalairway surfaces. Such concurrent or co-extensive application can beachieved by simultaneous administration, or by administrationsufficiently close in time so that a the two agents achieve theirtherapeutic effect concurrently.

[0076] Additional examples of receptor agonists that can be used tocarry out the present invention include those having the generalformula:

[0077] wherein:

[0078] A and B are each independently a purine or pyrimidine base (e.g.,adenine, guanine, thymine, cytosine, uracil); preferably, A is uraciland B is cytosine;

[0079] R₁ and R₂ are each independently selected from the groupconsisting of H or OH; and

[0080] n is from 1 to 5 or 6, preferably 2, 3 or 4.

[0081] The receptor agonists may be combined in the same formulation andadministered in like manner as the active compounds described above, oras described in U.S. Pat. Nos. 5,656,256 or 5,292,498, the disclosuresof which are to be incorporated by reference herein in their entirety.

[0082] The foregoing is illustrative of the present invention, and isnot to be construed as limiting thereof. The invention is defined by thefollowing claims, with equivalents of the claims to be included therein.

What is claimed is:
 1. A method of hydrating nasal airway surfaces in asubject in need of such treatment, comprising: topically applying asodium channel blocker to a nasal airway surface of said subject in anamount effective to inhibit the reabsorption of water by said nasalairway surface.
 2. A method according to claim 1 , wherein said patientis receiving nasal oxygen supplementation.
 3. A method according toclaim 1 , wherein said patient is afflicted with an allergic disorderaffecting nasal airway surfaces.
 4. A method according to claim 1 ,wherein said patient is afflicted with an inflammatory disorderaffecting nasal airway surfaces.
 5. A method according to claim 1 ,wherein said patient is afflicted with a bacterial infection of nasalairway surfaces.
 6. A method according to claim 1 , wherein said sodiumchannel blocker is a pyrazinoylguanidine sodium channel blocker.
 7. Amethod according to claim 6 , wherein said pyrazinoylguanidine sodiumchannel blocker has the formula:

wherein: X is selected from the group consisting of chloro, bromo, iodo,loweralkyl, lower-cycloalkyl having from 3 to 7 carbons, phenyl,chlorophenyl, bromophenyl, Z-thio and Z-sulfonyl wherein Z is selectedfrom the group consisting of loweralkyl and phenyl-loweralkyl; Y isselected from the group consisting of hydroxyl, mercapto, loweralkyloxy,loweralkylthio, chloro, loweralkyl, lowercycloalkyl having from 3 to 6carbons, phenyl, amino having the structure:

wherein R is selected from the group consisting of hydrogen, amino,amidino, lower-cycloalkyl having 3 to 6 carbon atoms, loweralkyl,hydroxyloweralkyl, halo-loweralkyl, lower-(cycloalkylalkyl) having 3 to6 carbons in the ring, phenyl-loweralkyl, lower-(alkylaminoalkyl),lower-alkenyl, phenyl, halophenyl, and lower-alkylphenyl; R₁ is selectedfrom the group consisting of hydrogen, loweralkyl, loweralkenyl, andadditionally; R and R₁ can be joined to form a lower alkylene; R₂ isselected from the group consisting of hydrogen and loweralkyl; and R₃and R₄ are independently selected from the group consisting of hydrogen,loweralkyl, hydroxy-loweralkyl, phenyl-loweralkyl,(halophenyl)-loweralkyl, lower-(alkylphenylalkyl),(loweralkoxyphenyl)-loweralkyl, naphthyl-loweralkyl,(octahydro-1-azocinyl)-loweralkyl, pyridyl-loweralkyl, and loweralkylradicals linked to produce with the nitrogen atom to which they areattached a 1-pyrrolidinyl, piperidino, morpholino, and a4-loweralkyl-piperazinyl group, and phenyl; or a pharmaceuticallyacceptable salt thereof.
 8. A method according to claim 1 , wherein X ischloro.
 9. A method according to claim 1 , wherein Y is amino.
 10. Amethod according to claim 1 , wherein R, R₁, and R₂ are hydrogen.
 11. Amethod according to claim 1 , wherein R₃ is hydrogen, phenyl, orphenylalkyl.
 12. A method according to claim 1 , wherein R₄ is hydrogen.13. A method according to claim 1 , further comprising the step oftopically applying a P2Y₂ receptor agonist to a nasal airway surface ofsaid subject in an amount effective to stimulate chloride secretion bysaid nasal airway surface.
 14. A method of hydrating a mucosal surfacein a subject in need of such treatment, comprising: topically applying asodium channel blocker to a nasal airway surface of said subject in anamount effective to inhibit the reabsorption of water by said mucosalsurface, wherein said sodium channel blocker is a covalent conjugate ofa pyrazinoylguanidine sodium channel blocker and a non-absorbablecarrier moiety.
 15. A method according to claim 14 , wherein saidmucosal surface is a nasal airway surface and said patient is receivingnasal oxygen supplementation.
 16. A method according to claim 14 ,wherein said mucosal surface is a nasal airway surface and said patientis afflicted with an allergic disorder affecting nasal airway surfaces.17. A method according to claim 14 , wherein said mucosal surface is anasal airway surface and said patient is afflicted with an inflammatorydisorder affecting nasal airway surfaces or a bacterial infection of thenasal airway surfaces.
 18. A method according to claim 14 , wherein saidnon-absorbable carrier moiety is selected from the group consisting ofcarbohydrates, proteins, peptides, polyamines, and water soluble linearpolymers.
 19. A method according to claim 18 , wherein saidnon-absorbable carrier moiety is a water soluble linear polymer selectedfrom the group consisting of polyvinylpyrrolidone, poyethylene glycol,nonylphenol ethoxylates, polyvinyl alcohol.
 20. A method according toclaim 18 , wherein said non-absorbable carrier moiety is a carbohydrateselected from the group consisting of sugars and polysaccharides.
 21. Amethod according to claim 18 , wherein said non-absorbable carriermoiety is a carbohydrate selected from the group consisting of dextran,lactose, sialic acid, and mannitol.
 22. A method according to claim 18 ,wherein said non-absorbable carrier moiety is a protein or peptideselected from the group consisting of albumin and protamine.
 23. Amethod according to claim 18 , wherein said non-absorbable carriermoiety is a polyamine selected from the group consisting of spermine andspermidine.
 24. A method according to claim 14 , wherein said conjugatehas the formula:

wherein: X is selected from the group consisting of chloro, bromo, iodo,loweralkyl, lower-cycloalkyl having from 3 to 7 carbons, phenyl,chlorophenyl, bromophenyl, X′-thio and X′-sulfonyl wherein X′ isselected from the group consisting of loweralkyl and phenyl-loweralkyl;Y is selected from the group consisting of hydroxyl, mercapto,loweralkyloxy, loweralkylthio, chloro, loweralkyl, lowercycloalkylhaving from 3 to 6 carbons, phenyl, amino having the structure:

wherein R is selected from the group consisting of hydrogen, amino,amidino, lower-cycloalkyl having 3 to 6 carbon atoms, loweralkyl,hydroxyloweralkyl, halo-loweralkyl, lower-(cycloalkylalkyl) having 3 to6 carbons in the ring, phenyl-loweralkyl, lower-(alkylaminoalkyl),lower-alkenyl, phenyl, halophenyl, and lower-alkylphenyl; R₁ is selectedfrom the group consisting of hydrogen, loweralkyl, loweralkenyl, andadditionally; R and R₁ can be joined to form a lower alkylene; R₂ isselected from the group consisting of hydrogen and loweralkyl; and Z isa non-absorbable carrier moiety covalently linked to the adjacentnitrogen atom; or a pharmaceutically acceptable salt thereof.
 25. Amethod according to claim 24 , wherein X is chloro and Y is amino.
 26. Amethod according to claim 24 , wherein X is chloro and Y is chloro. 27.A method according to claim 24 , wherein R, R₁, and R₂ are hydrogen. 28.A method according to claim 14 , further comprising the step oftopically applying a P2Y₂ receptor agonist to a mucosal surface of saidsubject in an amount effective to stimulate chloride secretion by saidmucosal surface.
 29. A pharmaceutical formulation, comprising: a sodiumchannel blocker in a pharmaceutically acceptable carrier; wherein saidsodium channel blocker is a covalent conjugate of a pyrazinoylguanidinesodium channel blocker and a non-absorbable carrier moiety; subject tothe proviso that said non-absorbable carrier moiety is not bovine serumalbumin or rabbit serum albumin.
 30. A pharmaceutical formulationaccording to claim 29 , said sodium channel blocker included in saidcomposition in an amount effective to inhibit the reabsorption of waterby mucosal surfaces.
 31. A pharmaceutical formulation according to claim29 , said sodium channel blocker included in said composition in anamount effective to inhibit the reabsorption of water by mucosalsurfaces.
 32. A pharmaceutical formulation according to claim 29 ,wherein said non-absorbable carrier moiety is selected from the groupconsisting of carbohydrates, proteins, peptides, polyamines, and watersoluble linear polymers.
 33. A pharmaceutical formulation according toclaim 29 , wherein said non-absorbable carrier moiety is a water solublelinear polymer selected from the group consisting ofpolyvinylpyrrolidone, polyethylene glycol, nonylphenol ethoxylates, andpolyvinyl alcohol.
 34. A pharmaceutical formulation according to claim29 , wherein said non-absorbable carrier moiety is a carbohydrateselected from the group consisting of sugars and polysaccharides.
 35. Apharmaceutical formulation according to claim 29 , wherein saidnon-absorbable carrier moiety is a carbohydrate selected from the groupconsisting of dextran, lactose, sialic acid, and mannitol.
 36. Apharmaceutical formulation according to claim 29 , wherein saidnon-absorbable carrier moiety is a protein or peptide selected from thegroup consisting of albumin and protamine.
 37. A pharmaceuticalformulation according to claim 29 , wherein said non-absorbable carriermoiety is a polyamine selected from the group consisting of spermine andspermidine.
 38. A pharmaceutical formulation according to claim 29 ,wherein said conjugate has the formula:

wherein: X is selected from the group consisting of chloro, bromo, iodo,loweralkyl, lower-cycloalkyl having from 3 to 7 carbons, phenyl,chlorophenyl, bromophenyl, X′-thio and X′-sulfonyl wherein X′ isselected from the group consisting of loweralkyl and phenyl-loweralkyl;Y is selected from the group consisting of hydroxyl, mercapto,loweralkyloxy, loweralkylthio, chloro, loweralkyl, lowercycloalkylhaving from 3 to 6 carbons, phenyl, amino having the structure:

wherein R is selected from the group consisting of hydrogen, amino,amidino, lower-cycloalkyl having 3 to 6 carbon atoms, loweralkyl,hydroxyloweralkyl, halo-loweralkyl, lower-(cycloalkylalkyl) having 3 to6 carbons in the ring, phenyl-loweralkyl, lower-(alkylaminoalkyl),lower-alkenyl, phenyl, halophenyl, and lower-alkylphenyl; R₁ is selectedfrom the group consisting of hydrogen, loweralkyl, loweralkenyl, andadditionally; R and R₁ can be joined to form a lower alkylene; R₂ isselected from the group consisting of hydrogen and loweralkyl; and Z isa non-absorbable carrier moiety covalently linked to the adjacentnitrogen atom; or a pharmaceutically acceptable salt thereof.
 39. Apharmaceutical formulation according to claim 38 , wherein X is chloroand Y is chloro.
 40. A pharmaceutical formulation according to claim 38, wherein X is chloro and Y is amino.
 41. A pharmaceutical formulationaccording to claim 38 , wherein R, R₁, and R₂ are hydrogen.
 42. Apharmaceutical formulation according to claim 29 , further comprising aP2Y₂ receptor agonist.
 43. A pharmaceutical formulation according toclaim 42 , said P2Y₂ receptor agonist included in an amount effective tostimulate chloride secretion by airway surfaces.
 44. A pharmaceuticalformulation according to claim 42 , said P2Y₂ receptor agonist includedin an amount effective to stimulate chloride secretion and watersecretion by airway surfaces.
 45. A pharmaceutical formulation accordingto claim 29 , wherein said carrier is an aqueous carrier solution.
 46. Acompound useful as a sodium channel blocker, said compound comprising acovalent conjugate of a pyrazinoylguanidine sodium channel blocker and anon-absorbable carrier moiety; subject to the proviso that saidnon-absorbable carrier moiety is not bovine serum albumin, rabbit serumalbumin or agarose.
 47. A compound according to claim 46 , wherein saidnon-absorbable carrier moiety is selected from the group consisting ofcarbohydrates, proteins, peptides, polyamines, and water soluble linearpolymers.
 48. A compound according to claim 46 , wherein saidnon-absorbable carrier moiety is a water soluble linear polymer selectedfrom the group consisting of polyvinylpyrrolidone, poyethylene glycol,nonylphenol ethoxylates, polyvinyl alcohol.
 49. A compound according toclaim 46 , wherein said non-absorbable carrier moiety is a carbohydrateselected from the group consisting of sugars and polysaccharides.
 50. Acompound according to claim 46 , wherein said non-absorbable carriermoiety is a carbohydrate selected from the group consisting of dextran,lactose, sialic acid and mannitol.
 51. A compound according to claim 46, wherein said non-absorbable carrier moiety is a protein or peptideselected from the group consisting of albumin and protamine.
 52. Acompound according to claim 46 , wherein said non-absorbable carriermoiety is a polyamine selected from the group consisting of spermine andspermidine.
 53. A compound according to claim 46 , wherein saidconjugate has the formula:

wherein: X is selected from the group consisting of chloro, bromo, iodo,loweralkyl, lower-cycloalkyl having from 3 to 7 carbons, phenyl,chlorophenyl, bromophenyl, X′-thio and X′-sulfonyl wherein X′ isselected from the group consisting of loweralkyl and phenyl-loweralkyl;Y is selected from the group consisting of hydroxyl, mercapto,loweralkyloxy, loweralkylthio, chloro, loweralkyl, lowercycloalkylhaving from 3 to 6 carbons, phenyl, amino having the structure:

wherein R is selected from the group consisting of hydrogen, amino,amidino, lower-cycloalkyl having 3 to 6 carbon atoms, loweralkyl,hydroxyloweralkyl, halo-loweralkyl, lower-(cycloalkylalkyl) having 3 to6 carbons in the ring, phenyl-loweralkyl, lower-(alkylaminoalkyl),lower-alkenyl, phenyl, halophenyl, and lower-alkylphenyl; R₁ is selectedfrom the group consisting of hydrogen, loweralkyl, loweralkenyl, andadditionally; R and R₁ can be joined to form a lower alkylene; R₂ isselected from the group consisting of hydrogen and loweralkyl; and Z isa non-absorbable carrier moiety covalently linked to the adjacentnitrogen atom; or a pharmaceutically acceptable salt thereof.
 54. Acompound according to claim 53 , wherein X is chloro and Y is chloro.55. A compound according to claim 53 , wherein X is chloro and Y isamino.
 56. A compound according to claim 53 , wherein R, R₁, and R₂ arehydrogen.